Ignition systems are used in automobiles' internal combustion engines to initiate a chemical reaction between fuel and air in the cylinder charge by producing a spark. The spark ignites the compressed air and fuel, thus resulting in downward movement of the piston contained within the cylinder.
Modem automotive ignition systems typically include an ignition coil and a coil current switching device. The ignition coil and coil current switching device respond to an input or “drive” signal to charge the ignition coil. The ignition coil thereafter relays high voltage to the spark plugs, allowing the spark to ignite the air and fuel in the cylinder that corresponds to the spark plug.
Various types of modem ignition systems exist. Two of such systems are hybrid and distributorless ignition systems. A hybrid ignition system may include a coil-over-plug assembly where the coil provides an output for the spark plug under the coil and also for the spark plug wire to the companion cylinder.
In the past, distributors were common components of ignition systems. A distributor is a rotary switch that directs the high voltage ignition current in a proper firing sequence to the various cylinders of an internal combustion engine. However, many modem ignition systems operate without a distributor. These systems are known as distributorless ignition systems (DIS). A common distributorless ignition system includes a single coil with two outputs for the connection of spark plugs to opposing cylinder spark plugs.
As is well known, an automobile's engine has several components which can malfunction or fail to operate. When engine problems occur, the automobile is often presented to a technician who must first identify the origin of the problem and then proceed to repair. It is desirable that such identification and repair be performed quickly and at a reasonable cost. From the various possible sources of engine problems, the technician is faced with narrowing down the origin of the problem prior to repair. The source might be the system for any one of smog reduction, driveability, induction, cooling, lubrication, sensors and ignition.
Using conventional diagnostic systems, diagnosing whether an ignition system is the source of engine problems can be complex and time-consuming. Although there are many ways to ascertain whether an ignition system is the source of engine problems, engine analyzers are one such method of making this determination. DIS and hybrid ignition systems are particularly difficult to analyze due to the single ignition coil being connected to two separate cylinders. A typical scenario for ignition system analysis for a four-cylinder vehicle begins with moving a 2-½ feet wide, 2 feet deep and 5 feet tall engine analyzer to the vehicle for usage. A number of cables must then be sorted through to find four connecting cables and four push-on KV clips (two push-on clips for a hybrid ignition system due to one inaccessible plug wire). The firing order of the cylinders as well as the cylinder numbering scheme must also be determined. The switched side of the coil must be located, and push on clips are installed per the firing order with cylinder one first. Coil polarity may also need to be determined.
The analysis process continues when the engine is started and run at normal idle. With some analyzers, when the analyzer scope is properly set, the firing order is displayed. Because there are two firing lines, one for the power stroke, and one for the waste stroke, one should be read for each cylinder. Leads must be moved for each coil. In this process, a faulty cylinder in an ignition system is generally identified by the technician from the analyzer's visual display as the power firing line that is different from the others. It is only at this point that the technician proceeds to repair. This method involves a number of steps, which results in complexity and consumption of time. Because an engine analyzer is required for this process, the process becomes more expensive.
There is a need for a vehicle diagnostic method and system that provide a simpler, more efficient way to determine whether an ignition system is the source of engine problems.
There is a need for a vehicle diagnostic method and system that provide a cost-efficient way to determine whether an ignition system is the source of engine problems.